Error on standard module Categories on 2 Levels

-- HikaShop version -- : 2.3.3
-- Joomla version -- : 3.3.6
-- PHP version -- : 5.3.29
-- Error-message(debug-mod must be tuned on) -- : Warning: trim() expects parameter 1 to be string, array given in /home/deb3757n234/domains/ledverlichting-lammers.nl/public_html/hikashop/libraries/framework/Joomla/Registry/Format/Json.php on line 49

I activated the Categories on 2 Levels module which is created on install of Hikashop. When I activate it I get the following error: Warning: trim() expects parameter 1 to be string, array given in /home/deb3757n234/domains/ledverlichting-lammers.nl/public_html/hikashop/libraries/framework/Joomla/Registry/Format/Json.php on line 49

I didn't changed any of the settings, just activated it.

Hope you can point me in the right direction for a fix...

Found the solution myself... There was something wrong with my custom module chrome.
Topic closed!